The present invention relates to an arrangement for setting the position of a guide bar on a chain saw relatively to the saw body.
The guide bar attachment on a chain saw is generally so designed that the guide bar can be displaced in its longitudinal direction within a limited setting area before the position is locked by means of guide bar bolts. In the Swedish Patent Specification SE-P-7401345.9 there is described a means for displacing the guide bar forwards and in that way effect a stretching of the saw chain on the guide bar. The arrangement thus known comprises a rack attached to the guide bar. Moreover, it comprises a tooth wheel projecting on the outside of the guide bar attachment and being in engagement with the rack. It is also rotatably mounted on one of the guide bar bolts. The arrangement is principally located in the cover above the guide bar attachment and shall thus be fitted against the guide bar mounted on the bolts. The application of the cover is therefore by many saw operators considered unnecessarily troublesome and time wasting as it involves a careful adaptation of several parts. It is therefore considered important to redesign the arrangement so that its components are located in a saw body. In doing so, the arrangement and the guide bar form a unity when the cover is to be put on.
The solution of the problem presented by the present invention is based on the principle to move the guide bar in its attachment by means of a cog-wheel and a straight toothed section. Such a principle offers in this case a simpler construction and a better location compared with that of the prior art. Other advantages of it are good accessibility in respect of the adjustment unit, rapid displacement of the guide bar without any pre-positioning of the same when it is fitted. Those advantages are obtained when the arrangement is made according to the characteristics of claim 1.